E2A Breakapart - Detail

Translocations involving the E2A gene have been characterised in childhood B-ALL. At present, there are two partner genes, PBX1 and HLF (on chromosomes 1 and 17 respectively) which become fused to E2A as a result of the t(1;19) and t(17;19) translocations forming the E2A/PBX1 and E2A/HLF fusion proteins respectively. The former is more common, being present in about 5% of paediatric ALLs whilst the other is present in some 1%. Both are associated with poor outcome. Detection of the t(1;19) is best carried out using molecular methods such as FISH as the fusion has been shown to be missed in 20 to 25% of patients by standard cytogenetics.